Securing Android The Hard Way

Recently Google has announced Android 12 , reltively less people use the newer version of Android. On a side note, Android is popularly used as compared to it’s competetions iOS which makes it juicy target for hackers.

You might ask this question why harden when default settings does the job.
Well, most of the defaults are not the best. So in this blog, I will document my
hardening journey aka “Securing” my Android phone running Android version 9.0 and some intresting findings.

Bloatware

Bloatware are those apps which come installed by Default on Android Devices.These are usually Dangerous apps(not necessarly) and may collect User’s Data in the Background. You can read more about Bloatware here

They can be removed by Enabling ADB Brdige on your Device and then run the following command
pm uninstall –k ––user 0 <name of package>

which essentially uninstalls the package for the user 0(which is you).
For more detailted steps checkout this arctile
From my knowledge, MIUI or any other customized vendor specific Android ROM’s have most number of Bloatware’s installed as compared to AOSP.
You can also look at Universal Android Debloater GUI tool to debloat your device via GUI.

App’s running in Background

Many apps tend to run in the backgroud even if you remove them from your recent applications window.(Well that’s how you get Notifications :P)

This is annoying due to following reasons:

• If a application is running in Background it consumes Battery, RAM andd Mobile Data tp sync making the device slow(when RAM <= 4GB)
• As we give all the Sensor permissions(Camera/Microphone) to these apps for their functionaliy, they can stalk you in the Background(since they aren’t closed) and this can be used for Targetted Advertising which is the worst part.
• When you are using VPN on your Android device, Google Apps sync in the Background(asscoiating your VPN IP with your Google Account)

We can stop apps running in background using a App called Greenify and it works on non-rooted phones as well. In the latest verion of Android we can enable Battery saver mode and that does the job, but an added advantage of Greenify is that you can Force stop aka “Hibernate” system apps like Google Chrome, Playstore which gives you more control on your phone.Setting up Greenify is pretty easy and you can lookup on the Internet.
There are other alternatives you can checkout which are Brevent , Doze, Naptime.

My Observation’s

• If you Greenify system apps, they get started in the background when they are required.
  For example, if you force stop Phone app and whenever you get a call, it starts in the background.
• Sometimes, some apps get invoked by some actions or invoke other apps in return
  For example, Zomato app starts running in the Background whenever you get a Call on your phone and when you normally open Zomato App, it opens Google Pay App in the Background.

By essentially force stopping these apps in the background, you can prevent these apps from snooping your microphone in the background.

Network

Whenever a malicous app is installed, it conects back to it’s C&C Server via network and having restrcitins at network level plays a vital role. Unlike Desktop Computer’s, Android gives us very less control on the Network flowing in and out of Device. We can take advantage of VPN Service in Android to monitor our traffic.

To harden our Netwrok Traffic, we can use a App called No Root Firewall.